In the past, rotary type fluid machines with an eccentric rotary piston mechanism have been known. This eccentric rotary piston mechanism is configured such that the ring-like piston moves in an eccentric rotation motion within a ring-like cylinder chamber. As such a rotary type fluid machine, there is a compressor, such as one disclosed, for example, in JP-A-H06-288358, which is configured to compress refrigerant by the variation in volume of the cylinder chamber associated with the eccentric rotation motion of the ring-like piston.
Referring to FIG. 19, the compressor of the aforesaid patent document has a cylinder (121) having a ring-like cylinder chamber (C1, C2) and a ring-like piston (122) disposed in the cylinder chamber (C1, C2). The cylinder (121) is composed of an external side cylinder (124) and an internal side cylinder (125). These cylinders (124) and (125) are arranged concentrically with each other. In other words, the cylinder chamber (C1, C2) is defined between the external side cylinder (124) and the internal side cylinder (125), and the cylinder chamber (C1, C2) is divided by the ring-like piston (122) into an external side cylinder chamber (C1) and an internal side cylinder chamber (C2). The ring-like piston (122) is configured such that it moves in an eccentric rotation motion with respect to the center of the cylinder (121) while the external peripheral surface of the ring-like piston (122) is in contact with the internal peripheral surface of the external side cylinder (124) substantially at one point and the internal peripheral surface of the ring-like piston (122) is in contact with the external peripheral surface of the internal side cylinder (125) substantially at one point.
An external side blade (123A) is disposed on the outside of the ring-like piston (122). An internal side blade (123B) is arranged on the inside of the ring-like piston (122) such that it is positioned on an extension of the external side blade (123A). The external side blade (123A) is inserted into the external side cylinder (124) and is biased inwardly in the radial direction of the ring-like piston (122) so that its tip is in pressure contact with the external peripheral surface of the ring-like piston (122). On the other hand, the internal side blade (123B) is inserted into the internal side cylinder (125) and is biased outwardly in the radial direction of the ring-like piston (122) so that its tip is in pressure contact with the internal peripheral surface of the ring-like piston (122). The external side blade (123A) divides the external side cylinder chamber (C1) into a high pressure chamber and a low pressure chamber. The internal side blade (123B) divides the internal side cylinder chamber (C2) into a high pressure chamber and a low pressure chamber. And in the above compressor, with the eccentric rotation motion of the ring-like piston (122), the suction of fluid is carried out in the low pressure chamber of each cylinder chamber (C1, C2) while the compression of fluid is carried out in the high pressure chamber of each cylinder chamber (C1, C2).